An airline spokesperson said the carrier managed to resume services from Heathrow Terminal 5 after it resolved a temporary technical issue it experienced earlier in the day.
"We deeply regret that we have now had to cancel some of our flights this evening," they added.
"We are taking steps to ensure as many customers as possible travel as planned. We have apologised to our customers for the inconvenience we have caused them, are offering to refund or rebook them onto alternative flights and providing refreshment vouchers and hotel accommodation where needed."
It comes after the airline was forced to cancel all short-haul flights at Heathrow last month owing to a technical issue.
